HISTOLOGICAL AND BIOADHESION STUDIES ON BUCCAL BIOADHESIVE TABLETS CONTAINING A PENETRATION ENHANCER SODIUM GLYCODEOXYCHOLATE

For many drugs, buccal route offers many advantages over conventional routes of delivery with an improved bioavailability due to the avoidan ce of degradation in the gastrointestinal tract and hepatic first-pass metabolism. However, the major limitation to buccal drug delivery is the permeability barrier in the buccal mucosa. Use of penetration enha ncers appears to be a pertinent approach to increase the drug permeati on through the buccal epithelium. Buccal bioadhesive tablet formulatio ns enable a delivery with a plasma drug level of the desired therapeut ic response for a defined period of time, and also provides a means of confining the drug and penetration enhancer to a defined region of th e mucosa. In this study, a bioadhesive tablet formulation for buccal d elivery was designed using a mixture of hydroxypropyl methylcellulose and carbomer, incorporated with a penetration enhancer, sodium glycode oxycholate (GDC). In vitro bioadhesion property of the formulated tabl et was examined and histological study was carried out to examine an i n vivo interaction between the tablet and tissue. GDC did not affect t he adhesiveness of the tablet which makes it an acceptable excipient f or a buccal bioadhesive drug delivery system. Histological changes suc h as loss of upper cell layers and formation of vacuoles as well swell ing in the cells were observed in the buccal epithelium, after 4 h con tact with the tablets containing GDC. Studies on reversibility of the interaction are in progress. (C) 1998 Elsevier Science B.V. All rights reserved.